Camshaft adjusters are used in internal combustion engines for varying the timing of the combustion chamber valves in order to be able to variably configure the phase relation between a crankshaft and a camshaft in a defined angular range between a maximum advanced position and a maximum retarded position. Adapting the timing to the instantaneous load and speed decreases the fuel consumption and reduces the emissions. For this purpose, camshaft adjusters are integrated into a drive train, via which a torque is transmitted from the crankshaft to the camshaft. This drive train may be designed as a belt drive, chain drive, or gearwheel drive, for example.
In a hydraulic camshaft adjuster, the output element and the drive element form one or multiple pairs of oppositely acting pressure chambers which may be acted on by hydraulic medium. The drive element and the output element are situated coaxially. The filling and emptying of individual pressure chambers generates a relative movement between the drive element and the output element. The spring acting rotatively between the drive element and the output element pushes the drive element with respect to the output element in a preferred direction. This preferred direction may be the same as or opposite to the rotation direction.
The vane cell adjuster is one design of the hydraulic camshaft adjuster. The vane cell adjuster includes a stator, a rotor, and a drive wheel having external teeth. The rotor is designed as an output element, usually having a design that is connectable to the camshaft in a rotatably fixed manner. The drive element contains the stator and the drive wheel. The stator and the drive wheel are connected to one another in a rotatably fixed manner, or alternatively are designed as one part. The rotor is situated coaxially with respect to the stator, and within the stator. With their radially extending vanes, the rotor and the stator form oppositely acting oil chambers which may be acted on by oil pressure and which allow a relative rotation between the stator and the rotor. The vanes are designed either as one part with the rotor or the stator, or as an “inserted vane” in grooves in the rotor or the stator which are provided for this purpose. In addition, the vane cell adjusters have various sealing covers. The stator and the sealing covers are secured to one another via multiple screw connections.
Another design of the hydraulic camshaft adjuster is the axial piston adjuster. A displacement element is axially displaced via oil pressure, and via helical teeth generates a relative rotation between a drive element and an output element.
Another design of a camshaft adjuster is the electromechanical camshaft adjuster, which includes a three-shaft gear (a planetary gear, for example). One of the shafts forms the drive element, and a second shaft forms the output element. Rotational energy may be supplied to the system or discharged from the system via the third shaft with the aid of an actuating device, for example an electric motor or a brake. A spring which assists with or returns the relative rotation between the drive element and the output element may be additionally provided.
DE 10 2011 007 883 A1 describes a camshaft adjuster which includes two output elements and one drive element, which include vanes which in the axial direction overlap with the lateral surfaces of the particular adjacent element.